Field of the Invention
Example embodiments relate generally to a system and method for throughput prediction that includes computing a wireless coverage map in order to provide a mechanism for mobile applications to adapt to wireless conditions, and likewise to provide a mechanism for mobile operators to optimize and balance wireless network resources, in order to control an operation of mobile services to improve a user's quality of experience.
Related Art
FIG. 1 illustrates a conventional 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE) network 10. The network 10 includes an Internet Protocol (IP) Connectivity Access Network (IP-CAN) 100 and an IP Packet Data Network (IP-PDN) 1001. The IP-CAN 100 generally includes: a serving gateway (SGW) 101; a packet data network (PDN) gateway (PGW) 103; a policy and charging rules function (PCRF) 106; a network management function (NMF) 107; a mobility management entity (MME) 108 and E-UTRAN Node B (eNB) 105 (i.e., base station, for the purposes herein the terms base station and eNB are used interchangeably). Although not shown, the IP-PDN 1001 portion of the EPS may include application or proxy servers, media servers, email servers, etc.
Within the IP-CAN 100, the eNB 105 is part of what is referred to as an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (EUTRAN), and the portion of the IP-CAN 100 including the SGW 101, the PGW 103, the PCRF 106, the NMF 107 and the MME 108 is referred to as an Evolved Packet Core (EPC). Although only a single eNB 105 is shown in FIG. 1, it should be understood that the EUTRAN may include any number of eNBs. Similarly, although only a single SGW, PGW and MME are shown in FIG. 1, it should be understood that the EPC may include any number of these core network elements.
The eNB 105 provides wireless resources and radio coverage for one or more user equipments (UEs) 110. That is to say, any number of UEs 110 may be connected (or attached) to the eNB 105. The eNB 105 is operatively coupled to the SGW 101, the NMF 107, and the MME 108.
The SGW 101 routes and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNB handovers of UEs. The SGW 101 also acts as the anchor for mobility between 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE) and other 3GPP technologies. For idle UEs 110, the SGW 101 terminates the downlink data path and triggers paging when downlink data arrives for UEs 110.
The PGW 103 provides connectivity between UE 110 and the external packet data networks (e.g., the IP-PDN) by being the point of entry/exit of traffic for the UE 110. As is known, a given UE 110 may have simultaneous connectivity with more than one PGW 103 for accessing multiple PDNs.
The PGW 103 also performs policy enforcement, packet filtering for UEs 110, charging support, lawful interception and packet screening, each of which are well-known functions. The PGW 103 also acts as the anchor for mobility upon SGW relocation during handovers within LTE network, as well as between 3GPP and non-3GPP technologies, such as Worldwide Interoperability for Microwave Access (WiMAX) and 3rd Generation Partnership Project 2 (3GPP2 (code division multiple access (CDMA) 1× and Enhanced Voice Data Optimized (EvDO)).
Still referring to FIG. 1, eNB 105 is also operatively coupled to the MME 108. The MME 108 is the control-node for the EUTRAN, and is responsible for idle mode UE 110 paging and tagging procedures including retransmissions. The MME 108 is also responsible for choosing a particular SGW for a UE during initial attachment of the UE to the network, and during intra-LTE handover involving Core Network (CN) node relocation. The MME 108 authenticates UEs 110 by interacting with a Home Subscriber Server (HSS), which is not shown in FIG. 1.
Non Access Stratum (NAS) signaling terminates at the MME 108, and is responsible for generation and allocation of temporary identities for UEs 110. The MME 108 also checks the authorization of a UE 110 to camp on a service provider's Public Land Mobile Network (PLMN), and enforces UE 110 roaming restrictions. The MME 108 is the termination point in the network for ciphering/integrity protection for NAS signaling, and handles security key management.
The MME 108 also provides control plane functionality for mobility between LTE and 2G/3G access networks with an S3 type of interface from the SGSN (not shown) terminating at the MME 108.
The Policy and Charging Rules Function (PCRF) 106 is the entity that makes policy decisions and sets charging rules. It has access to subscriber databases and plays a role in the 3GPP architecture as specified in 3GPP TS 23.203 “Policy and Charging Control Architecture.” The network management function (NMF) 107 is the entity that controls operations of the Radio Access Network.
The IP-PDN 1001 network may include an application function (AF) 109. The Application Function (AF) 109 is an entity that is application aware and is an ultimate receiver of exported eNB data that may be used to more effectively deliver content to the UE 110 to improve and/or optimize the network 10. AF 109 may alternatively or additionally be positioned inside the UE 110.
FIG. 2 illustrates a conventional E-UTRAN Node B (eNB) 105. The eNB 105 includes: a memory 240; a processor 220; a scheduler 210; wireless communication interfaces 260; Radio Link Control (RLC) and Medium Access Control (MAC) layer control 230 for each bearer; and a backhaul interface 235. The RLC and MAC layer control 230 is responsible for RLC and MAC layer protocol signaling, as defined by the 3GPP standards. The processor or processing circuit 220 controls the function of eNB 105 (as described herein), and is operatively coupled to the memory 240 and the communication interfaces 260. While only one processor 220 is shown in FIG. 2, it should be understood that multiple processors may be included in a typical eNB 105. The functions performed by the processor may be implemented using hardware. Such hardware may include one or more Central Processing Units (CPUs), digital signal processors (DSPs), application-specific-integrated-circuits, field programmable gate arrays (FPGAs) computers or the like. The term processor, used throughout this document, may refer to any of these example implementations, though the term is not limited to these examples. With a Virtual Radio Access Network (VRAN) architecture various functions eNB components may be distributed across multiple processing circuits and multiple physical nodes within VRAN cloud.
The eNB 105 may include one or more cells or sectors serving UEs 110 within individual geometric coverage sector areas. Each cell individually may contain elements depicted in FIG. 2. Throughout this document the terms eNB, cell or sector shall be used interchangeably.
Still referring to FIG. 2, the communication interfaces 260 include various interfaces including one or more transmitters/receivers connected to one or more antennas to wirelessly transmit/receive control and data signals to/from UEs 110, or via a control plane. Backhaul interface 235 is the portion of eNB 105 that interfaces with SGW 101, MME 108, other eNBs, or interface to other EPC network elements and/or RAN elements within IP-CAN 100. The scheduler 210 schedules control and data communications that are to be transmitted and received by the eNB 105 to and from UEs 110. The memory 240 may buffer and store data that is being processed at eNB 105, transmitted and received to and from eNB 105.
Every Transmission Time Interval (TTI), typically equal to 1 millisecond, the scheduler 210 may allocate a certain number of Physical Resource Blocks (PRBs) to different bearers carrying data over the wireless link in the downlink direction (i.e., transmitting buffered data from eNB 105 to UE 110) and uplink direction (i.e., receiving data at eNB 105 from UE 110, which is received over backhaul 235). A “bearer” may be understood to be a virtual link, channel, or data flow used to exchange information for one or more applications on the UE 110. The scheduler 210 may determine Modulation and Coding Schema (MCS) that may define how many bits of information may be packed into the allocated number of PRBs. The latter is defined by the 3GPP TS36.213 tables 7.1.7.1-1 and 7.1.7.2.1-1 (the contents of which is incorporated by reference in its entirety), which presents a lookup table for a number of bits of data that may be included in PRBs sent per TTI for a given allocated number of PRBs and a MCS value. MCS is computed by the scheduler and RLC/MAC control using Channel Quality Indicator (CQI) values reported by the UE 110 that in turn may be derived from measured UE 110 wireless channel conditions in the form of Signal to Interference and Noise Ratio (SINR).
Scheduler 210 may make PRB allocation decisions based upon a Quality of Service (QoS) Class Identifier (QCI), which represents traffic priority hierarchy. There are nine QCI classes currently defined in LTE, with 1 representing highest priority and 9 representing the lowest priority. QCIs 1 to 4 are reserved for Guaranteed Bitrate (GBR) classes for which the scheduler maintains certain specific data flow QoS characteristics. QCIs 5 to 9 are reserved for various categories of Best Effort traffic.
Conventionally, a wireless coverage map may be assembled as a location-based wireless signal quality indicator, such as SINR (Signal to Interference and Noise Ratio), which may be used to calculate bearer throughput. Such signal quality indicator data is typically assembled either based upon designated measurements with drive tests conducted using dedicated equipment by wireless service providers, or based upon assembled signal quality reports received from UEs. However, such conventional coverage maps do not provide adequate data for computing expected application bearer throughput with the necessary certainty and accuracy to be meaningfully used by mobile applications, especially in LTE and emerging 5G networks. In particular, conventional coverage maps do not provide an inexpensive means of representing signal quality indication, with necessary error margins of 10% or less (i.e., an error of 100 Kbps or less on a 1 Mbit/sec throughput) that may support mobile applications in recently advancing networks.
Additionally, while conventional coverage maps based upon designated measurements with drive tests conducted using dedicated testing equipment by wireless service providers may be relatively accurate, these coverage maps can be prohibitively expensive to produce. Therefore, these drive tests are not realistic for all possible UE locations with all permutations of neighboring cell loads (which affect interference) and weather conditions (e.g. rain or dust in the air affect noise levels). And, conventional coverage maps based upon assembled signal quality reports compiled from UEs are less accurate, as the compiled data from UEs is typically sourced from an application level (or alternatively a MAC level), the data from the reports is relatively sparse, and the data is generally not sufficiently accurate because interference variations due to permutations of neighboring cell load is not accounted for in the UE reports.
Finally, none of the conventional schemes for producing coverage maps provide direct and sufficiently accurate indication of a number of bits per wireless physical resource block (PRB) as a channel conditions characteristic. For example, in LTE a Modulation and Coding Schema (MCS) may be derived from Channel Quality Indicator (CQI) reports from UEs. However, even for stationary UEs, observed MCS variations during 1 sec time intervals (as computed at eNodeB RLC and scheduler layers) may be large enough to experience a more than 200% variation in estimated throughput, due in part to fluctuations in channel conditions.